In order to precisely evaluate the lighting performance of our headlamps, Petzl has developed a thorough protocol for taking specific measurements. Results obtained in this way allow us to compare the lighting performance of many different headlamps. This information makes it easy for the user to make a choice based on his needs or personal criteria.
Petzl's measurement protocol is applied to tests performed in the lab on five completely identical headlamps. These headlamps are selected randomly directly from the production line. These headlamps are tested one by one with two new sets of the same type of batteries that are included with the headlamps (alkaline or rechargeable). Headlamps that do not come with batteries are tested with new alkaline batteries. In order to maintain a stable testing environment and statistically significant results, particularly with regard to batteries, all measurements are taken at 20 °C.
The final, definitive result for each parameter being tested represents the average of the ten measurements (five headlamps and two energy sources).
RD lighting research - photo T.Marchand
Before measuring lighting distance and burn time, it is useful to have a definition of the minimum amount of light below which a headlamp is no longer effective, i.e., when the lighting level becomes too low for adequate vision. Petzl has evaluated this illumination level to be equivalent to the light emitted from a full moon on a clear night, or 0.25 lux. This minimum lighting level is used as a reference for measuring lighting distance and duration.
The luminous flux is the total quantity of light emitted in every direction from a source of light. Luminous flux is expressed in lumens (lm). It is measured in the lab, with the help of an integrated sphere device. This measurement is complementary to the lighting distance. Two light sources can in fact shine at the same distance with different intensities. As with lighting distance, luminous flux diminishes as the energy source drains. Petzl indicates luminous flux in maximum mode, thus providing the user with the maximum possible output of each light.
Some lumen equivalencies:
- candlelight: 10 lumens
- TIKKA PLUS2 (maximum mode): 50 lumens,
- DUO LED 14 (maximum mode): 67 lumens,
- household lighting: 100 to 200 lumens,
- ULTRA (maximum mode) : 350 lumens.
Battery life is defined as the length of time that a headlamp illuminates at 0.25 lux or more from a distance of two meters. When the light produced is lower than this level, we consider that the headlamp is no longer usable, whether for walking, reading, or any other activity.
Regulated headlamps are equipped with an electronic regulating mechanism that maintains a constant lighting distance for a given amount of time.
This distance/time association is indicated with the performance information of the headlamp. Once the available electric energy is no longer sufficient, the regulation automatically stops. In this case, the lighting strength diminishes to survival lighting to allow the user enough time to change the batteries.
For non-regulated headlamps, lighting distance decreases progressively as the energy source is drained.
Lighting distance measurements are performed:
- after 30 minutes of use (limited and short use)
- after 10 hours of use (continuous use)
- after 30 hours of use
Petzl considers signal lighting to be efficient when visible from 100 m or more. Under this distance, the lighting is not sufficient for being seen and ensuring adequate safety.
Battery life is defined as the length of time that the headlamp produces signal lighting that illuminates at 0.00001 lux or more from a distance of 100 m